Fig. 1. Topological placement of taxa in the Yellowstone Lake food web before (left) and after (right) invasion by nonnative lake trout.

The conceptualization (nonmathematical) emphases are the cutthroat trout (YCT) and other components known (black arrows) or hypothesized (orange arrows) to be affected by the introduction of lake trout (LKT). Thick arrows indicate that the consumption of that food item is high by predator or herbivore, and thin arrows indicate that the consumption is low, within the aquatic (below the blue line) and across terrestrial (above the blue line) ecosystems. Letters represent consumption of (A) phytoplankton, (B) zooplankton, (C) amphipods, (D to G) cutthroat trout, (H) longnose suckers, (I) elk calves, and (J) common loon, trumpeter swan, American white pelican, double-crested cormorant, and Caspian tern. Organisms are not drawn to scale, although the size of the fish, osprey, and otter depicts observed shifts in abundance between periods. California gulls were present before lake trout invasion but no longer nest on Yellowstone Lake.